What to say when someone calls you a moron

When a verbal bully calls you a moron you may be taken aback, even a little startled. After all, it is a very nasty thing to say to someone.
Some people think you should just ignore it, but if you do there is a pretty good chance the person will think you are an easy target, and they will probably single you out for more abuse in the future.
When an idiot calls you a moron, use of our snarky comebacks below. Vote for what you think is the best answer.